/**
 * Copyright 2006 gworks.com.au
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. (http://www.apache.org/licenses/LICENSE-2.0)
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed 
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for 
 * the specific language governing permissions and limitations under the License.
 *
 * <dhamma-message src="Atisha (11th century Tibetan Buddhist master)">
 * 	The greatest achievement is selflessness. The greatest worth is self-mastery.
 * 	The greatest quality is seeking to serve others. The greatest precept is continual awareness.
 * 	The greatest medicine is the emptiness of everything. The greatest action is not conforming with the worlds ways.
 * 	The greatest magic is transmuting the passions. The greatest generosity is non-attachment.
 * 	The greatest goodness is a peaceful mind. The greatest patience is humility.
 * 	The greatest effort is not concerned with results. The greatest meditation is a mind that lets go.
 * 	The greatest wisdom is seeing through appearances. 
 * </dhamma-message>
 */
package org.javaongems.server;

import java.util.Map;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

import org.apache.log4j.Logger;
import org.javaongems.runtime.lang.StringUtils;
import org.javaongems.server.GemEntryPointPager.ContextFactory;

/**
 * <p>Provides a basic keyed request parameter factory resolver implementation
 * </p>
 * <p>Responsibilities:
 * <ul>
 * 	<li> support configurability of keyed parameter and default value
 * 	<li> inspect the request's query string for the keyed parameter
 * 	<li> return the context factory associated with that keyed value, 
 * 		otherwise return the default factory
 * </ul>
 * </p>
 * @see GemEntryPointPager.ContextFactoryResolver
 * @author Ashin Wimalajeewa (ash)
 */
public class KeyedRequestParamFactoryResolver implements GemEntryPointPager.ContextFactoryResolver {
	final static private Logger LOGGER = Logger.getLogger(KeyedRequestParamFactoryResolver.class);
	final static public String KEY_PARAM = "KeyedRequestParamFactoryResolver.key";
	final static public String DEFAULT_VAL_PARAM = "KeyedRequestParamFactoryResolver.defaultVal";
	final static public String DEFAULT_KEY_NAME = "action";
	final static public String DEFAULT_VAL = "default";
	
	protected String key;
	protected String defaultVal;
	protected ContextFactory defaultFactory;
	
	public ContextFactory getContextFactory(HttpServletRequest req, Map<String, ContextFactory> contexts) {
		String action = req.getParameter(key);
		ContextFactory delegate = contexts.get(action);
		if (delegate == null) 
			delegate = defaultFactory;
		if (LOGGER.isDebugEnabled()) LOGGER.debug("using factory: " + delegate);
		return delegate;
	}

	public void setServletConfig(ServletConfig cfg, Map<String, ContextFactory> contexts) throws ServletException {
		key = cfg.getInitParameter(KEY_PARAM);
		if (StringUtils.isEmpty(key))
			key = DEFAULT_KEY_NAME;
		defaultVal = cfg.getInitParameter(DEFAULT_VAL_PARAM);
		if (StringUtils.isEmpty(defaultVal))
			defaultVal = DEFAULT_VAL;
		defaultFactory = contexts.get(defaultVal);
		LOGGER.info("registering default factory [" + defaultVal + "]");
	}
}
